Core plug heater



United States Patent 3,456,094 CORE PLUG HEATER John H. Klancke and Seth B. Lindsey, Minneapolis, Minn, assignors to Phillips Manufacturing Company, Inc., Minneapolis, Minn., a corporation of Minnesota Filed June 20, 1966, Ser. No. 558,905 Int. Cl. B601 1/06 US. Cl. 219208 11 Claims ABSTRACT OF THE DISCLOSURE A heater for automotive engines includes a plug carrying an electric heating element adapted to be positioned within the engine when the plug is mounted in a core plug hole on the engine. A compressible sealing member trapped between a pair of annular clamping washers surrounds the plug. Means are provided to axially compress the washers and sealing member, thus causing the washers to expand radially to bite the surface of the hole to mechanically lock the plug in place and causing the sealing member to expand circumferentially to seal the space between the plug and the surface of the hole. The pair of washers prevent extrusion of the sealing member upon compression.

This invention relates to core plug heaters. More particstructed and arranged to perfect a more perfect seal while used in an automotive engine to retain a cooling liquid therein and bring or maintain such liquid to a temperature such as to facilitate starting of the automotive engine in cold weather.

Since heaters of this type are conventionally inserted in the frost plug hole of automotive engines or internal combustion engines, they are commonly referred to as core plug heaters. Actually, to install such a heater, the core plug or freeze plug of the engine is removed and the core plug heater is mounted in the hole in lieu thereof. Therefore, in describing the invention disclosed herein, we will refer to such a hole in an internal combustion engine as the core plug hole and will refer to our improved heating device as a core plug heater.

Automotive engines or internal combustion engines are cast with holes in the casting process by means of which sand utilized at this time may be eliminated from the casting. Thereafter, the bore of the hole is machined, but due to manufacturing tolerances the core plug holes vary in size and consequently it is desirable to make provision for such variances. Even more important, nonuniformities will be found in the wall structure of the engine which defines the core plug hole so that even though the core plug heater may be truly round, the discrepancies in the wall which defines the core plug hole will leave openings or leaks through which the sealing member may extrude when compressed axially of the core plug heater. Consequently, we have found that it is important if a perfect seal is to be accomplished that some provision be made to provide a core plug heater which, if possible, will obviate the undesirable characteristics of such an installation when the seal by means of which the heater is mounted within the engine has a fixed diameter and circumferential surface. We have found that we can overcome these disadvantages through the use of a pair of flexible steel clamping Washers and a sealing member therebetween which cooperate to bite into the relatively soft material of the engine which defines the core plug hole and trap the sealing member therebetween effectively so as to preclude extrusion and compress the sealing mem- 3,456,694 Patented July 15, 1969 her to cause the latter to expand circumferentially and thereby perfect a complete seal Without permitting extrusion of any portion of the sealing member. Moreover, we have found that by utilizing a beveled adaptor washer a single core plug heater constructed in accordance with our invention can be utilized for installation in core plug holes, within limits, of different diameters so as to accommodate to a much greater extent core plug holes which may have such different diameters as a result of the casting procedures by means of which the internal combustion engine has been constructed.

It is a general object of our invention to provide an improved core plug heater which will more effectively trap the sealing member and cause the same upon axial compression to more adequately perfect the seal within the core plug hole.

A more specific object is to provide an improved core plug heater which is simple in design, economical to manufacture and install, and will upon installation acomplish a more perfect seal than core plug heaters heretofore known. Another object is to provide an improved core plug heater constructed and arranged so as to enable a core plug heater of predetermined dimensions to be utilized in any one of a plurality of core plug holes which have various dimensions within limits so as to provide limited universal application of such core plug heaters despite dimensional discrepancies in the construction of such engines.

Another object is to provide an improved core plug heater constructed and arranged to provide a pair of clamping washers at opposite sides of a sealing element, the washers of which are capable of radial expansion upon axial compression and are made of a material sufficiently hard so as to bite into the core plug hole defining wall and thereby provide a more perfect seal while more positively mounting the heater within such an opening.

These and other objects and advantages of our invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

The improved core plug heater of our present invention is shown in exploded view in FIG. 1 with the general designation 10. As shown, it includes a metal tubular member or plug member 12 having an externally threaded end portion 14 and an annular flange portion 16 at the opposite extremity thereof which serves as an abutment means for the clamp washers to be hereinafter described. Intermediate the threaded portion 14 and the annular flange or shoulder portion 16 is a central portion 18 of intermediate diameter, the purpose of which will be later noted. Mounted within the metal tubular member 12 is a copper electrical heating element 20 which is conventional in construction and is similar to the heating element shown in US. Patent No. 2,783,352 issued to D. D. McKay, dated Feb. 26, 1957. While the heating element in the patent disclosure referred to above is preferable, it will be understood that other suitable electrical heating elements may be utilized within the scope of this invention. The heating element 20 has its extremities 21, 22 positioned in apertures or holes 23 extending through the plug member and which terminate in terminal conductors 24, 25 respectively in a recess 26 in the threaded outer end portion 14 of the plug member. The extremities 21, 22 are suitably sealed within the plug member 12 by a solder substance or epoxy resin to seal the ends of the heater element therein and thereby seal off the interior of the plug member 12 as it is assembled.

Mounted upon the plug member 12, as best shown in FIGS. 1 and 3, is a clamping washer 30 which has tapered surfaces and is made of a hardened steel material, such as stainless steel, with a predetermined spring rate. This type of washer is sometimes identified as a Belleville spring and when flattened by compression will expand radially to increase the diametrical or radial dimension of the same. The clamping washer 30 is positioned against the annular flange portion or abutment means 16 of the plug member 12 to bear against the same. Adjacent the clamping washer 30 is an annular sealing ring 32 which is made of a flowable elastic material, such as rubber, and may include fabric material embedded therein. The rubber ring 32 performs the sealing function for the core plug heater as will be hereinafter noted and is adapted to expand radially when compressed in an axial direction as will be hereinafter described.

Also mounted on the plug member 12 at the opposite side of the sealing ring 32 is a second clamping washer 34 constructed substantially identically and having substantially identical dimensions so as to bear against the opposite side of the sealing ring 32 and compress the same when axial compression is applied to the two washers. Also carried by the plug member 12 and bearing directly against the clamping washer 34 is an expander plate or ring 36 which has a fiat thrust surface 38. When mounted and actual compression is applied to the clamping washers and the expander plate 36, the latter causes the clamping washers 34 to increase their diametrical dimensions so as to bite into the wall which defines the core plug hole and secure the same therein. The expander plate 36 is preferably formed of metal.

Positioned behind the expander member 36 is an adaptor washer 40' which is preferably formed of metal and is annular in shape and has a beveled adaptor surface 42 and a thrust surface 44, the latter bearing against the expander ring 36 when the heater is mounted within the core plug hole. Positioned behind the adaptor ring 40 is a nut 46 threaded on the threaded end portion 14 of the plug member 12. Thus the nut 46 as so threaded, together with the adaptor washer 40 and expander ring 36, constitutes an effective expander means for the clamping washers 30 and 34.

FIG. 3 best shows the parts identified above in assembled relation within the wall of an engine which is indicated generally at 48 through a core plug hole 50 therein. The improved heater in assembled relationship normally has the nut 46 threaded on the threaded end portion of the plug member to such an extent that the adaptor ring 40 bears against the expander ring 36 which in turn brings the two clamping washers and the intermediately positioned sealing ring into close proximity and bearing against the abutment means 16 provided for that purpose. Thus as the nut 46 is tightened, all of these parts are brought into snug fitting relation and are urged against the flanged end portion 16 of the plug member 12 so that subsequent tightening of the nut 46 will cause the clamping washers 24 to be compressed axially and to expand so that their diameters will increase.

When the improved heater is assembled as described in the immediately preceding paragraph, it is adapted to be inserted into a core plug hole 50 of an engine 48. As shown, the heater element 20 has a diametrical dimension slightly less than the dimension of the flanged portion 16 so that the heater may be inserted into the core plug hole without engagement with the sides of the engine. Likewise, the diameters of the clamping washers 34 and the sealing ring 32 as well as the expander ring 36 are slightly less than the diameter of the core plug hole 50 so that assembly may be slipped into the hole 50 with the circumferential surfaces of these parts in close proximity therewith but not under pressure until subsequent to the tightening of the nut 46 so as to cause diametrical expansion of the clamping washers 30, 34. The improved heater is preferably installed by thrusting the assembled device into the core plug hole 50 until the tapered surface 42 of the adaptor plate 40 bears against the peripheral surface of the wall of the engine 48 which defines the opening 50 as best is shown in FIG. 3 and indicated by the numeral 52.

When it is desired to utilize the improved core plug heater 10, the elements of the same are assembled as described herein and the nut 45 is advanced on the threaded portion 14 so that the expander ring 36 will cause the clamping washers to expand sufficiently to closely approach the diameter of the core plug hole 50. The core plug heater is then positioned in the desired position as shown in FIG. 3 and the nut 45 is tightened to complete the expansion of the clamping members 30, 34 and cause the seal member 32 to be compressed therebetween, thereby causing the sealing ring 32 to expand circumferentially and perfect the seal against the wall which defines the opening 50. As the clamping Washers 30, 34 increase their diametrical, and hence their circumferential, dimensions they bite into the relatively soft wall which defines the opening 50 and positively trap the sealing ring 32 therebetween so as to preclude any possible extrusion of the sealing ring past either of the clamping washers. Thus the disadvantages which will otherwise result from the minor discrepancies in the dimensions of the engine that has been casted are completely overcome in that the clamping washers bite into the wall sufficiently to extend beyond such discrepancies in dimensions and positively encase and tray the sealing ring 32 therebetween. Thus as the sealing ring is compressed axially, it expands circumferentially and bears against the wall that defines the opening 52 between the two clamping washers 30, 34 and perfects a seal between the heater as an entirety and the engine wall to a much more perfect degree than has heretofore been possible with core plug heaters of conventional construction.

The spring steel clamp washers 30, 34, it will be noted, are each generally frusto-conically shaped in that their circumferential portions are included radially inwardly in an axial direction toward the flange portion 16. Thus when they are compressed by action of the expander plate 36 and nut 46, they will increase their radial and diametrical dimensions since they will thereby approach a plane normal to theiraxis. As a consequence they will bite into the relatively soft material of the engine which defines the opening 50 and will trap the sealing ring 32 therebetween so as to prevent extrusion thereof past either of the clamping washers.

It will also be noted that through the use of the beveled adaptor surface 42 of the adaptor plate 40, small variations in the diameter of the core plug hole can be overcome so as to provide a more universal application of the core plug heater. In other words, despite such variations in dimensions, a core plug heater of this type can be readily utilized for it has a range for all openings between the shorter diameter and the longer diameter of the beveled surface of the adaptor plate.

From the above it will be seen that we have provided an unusually simple, inexpensive, and more highly effectively sealed core plug heater than has been heretofore known. This core plug heater can be manufactured at a minimum of cost and be installed with a minimum of time and effort. The heater as applied effectively locks itself in position so as to preclude the loss of the heater element itself and/ or the cooling medium within the engine block. We have found that a core plug heater of this type is more satisfactory than any of the type heretofore known to us in the prior art.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of our invention which consists of the matter shown and described herein and set forth in the appended claims.

What is claimed is:

l. A core plug heater for automotive engines comprising:

(a) a plug member having an annular flange portion,

said plug member being adapted to be positioned an a core plug hole in an automotive engine with the flange portion having a dimension slightly less than the core plug hole and being normally positioned within said core plug hole,

(b) an electrical heating element mounted on said plug member and extending outwardly from the side thereof and adapted to be connected to an electrical power at the other side of the plug member, said heating element being adapted to be positioned Within the automotive engine when said plug member is mounted in a core plug hole therein,

(c) an annular sealing element carried by said plug member in encircled relation and bearing against said plug member, said sealing element being circumferentially expandable,

(d) a clamping washer having a characteristic of expanding radially when flattened by compression, positioned on said plug member at one side of said annular sealing element and between said flange portion and said sealing element and bearing against said flange portion when said plug member is so mounted,

(e) a second clamping washer having a characteristic of expanding radially when flattened by compression and positioned on said plug member at the opposite side of said annular sealing element and bearing thereagainst,

(f) said clamping washers and said sealing element when not under axial compression having radial dimensions slightly smaller than the core plug hole in the engine, and

(g) expander means carried by said plug member and having a thrust surface thereon axially movable relative to said plug member and with a radial dimension smaller than the core plug hole in the engine, said expander means when positioned on said plug member within the core plug hole in the engine having its thrust surface acting against said clamping washers and said sealing element to compress the washers such that they expand radially and bear against the interior surface in the core plug hole in the engine to secure the plug member therein and to compress the sealing element between said clamping washers such that its expands cir cumferentially and engages the surface of the core plug hole to seal the plug member in the core plug hole in the engine.

2. The structure defined in claim 1 wherein said expander means is threadably mounted on said plug member and includes an expander Washer movable axially of and encircling said plug member and carrying said thrust surface in compressing relation against said second clamping washer, an adapter washer movable axially of said plug member and having a thrust surface bearing against said expander washer and having an annular beveled surface bearing against the peripheral surface of the core plug hole to adapt the heater within limits to core plug holes of various diameters, and a nut threaded onto the the plug member and bearing against said adapter washer to cause said clamping washers and sealing element to be compressed and seal said plug member Within the core plug hole in the engine.

3. The structure defined in claim 1 wherein said clamping washers are of generally frusto-conical shape and are made of a material harder than the material in the automo ive engine in which it is mounted.

4; The structure defined in claim 1 wherein said clamping washers are each of the Belleville type.

5. The structure of claim 1 wherein said clamping washers are made of stainless steel and one thereof bears against said annular flange portion of said plug member with said sealing element positioned between said washers and being axially compressed by said expander means whereby said clamping Washers and said sealing element are each expanded circumferentially.

6. The structure defined in claim 1 wherein said clamping washers upon radial expansion imbed into the interior metal surface in the core plug hole in the automotive engine to secure the plug member therein and trap said sealing element therebetween to positively prevent extrusion thereof therebeyond.

7. The structure defined in claim 1 wherein said expander means includes an adapter washer movable axially of said plug member and which transmits axial compression to said clamping washers and has an annular beveled surface bearing against the peripheral surface of the core plug hole to adapt the heater within limits to core plug hole of various diameters, and a nut threaded onto the plug member and bearing against said adapter washer to cause said clamping washers and sealing element to be compressed axially and seal said plug member within the core plug hole in the engine.

8. A core plug heater for automotive engines comprising:

(a) a plug member adapted to be positioned in a core plug hole in an automotive engine and having abutment means thereon normally positioned within and having a dimension less than the core plug hole,

(b) an electrical heating element mounted on said plug member and extending outwardly from the side thereof and adapted to be connected to an electrical power at the other side of the plug member, said heating element being adapted to be positioned within the automotive engine when said plug member is mounted in a core plug hole therein,

(c) an annular sealing element carried by the plug member in encircled relation and bearing against the plug member, said sealing element being circumferentially expandable,

(d) a clamping washer having a characteristic of expanding radially when flattened by compression, positioned on said plug member at one side of said annular sealing element and between said abutment means and said sealing element and bearing against said abutment means when said plug member is so mounted,

(e) a second clamping washer having a characteristic of expanding radially when flattened by compression and positioned on said plug member at the opposite side of said annular sealing element,

(f) said clamping washers and said sealing element having radial dimensions slightly smaller than the core plug hole in the engine, and

(g) expander means carried by said plug member and having a thrust surface thereon movable axially relative to said plug member and having a radial dimension smaller than the core plug hole in the engine, said expander means when positioned on said plug member within the core plug hole in the engine having its thrust surface acting against said clamping washers and said sealing element to compress the washers such that they expand radially and bear against the interior surface in the core plug hole in the engine to secure the plug member therein and to compress the sealing element between said clamping Washers such that it engages the surface of the core plug hole to seal the plug member in the core plug hole in the engine.

9. The structure defined in claim 8 wherein said expander means is threadably mounted on said plug member and includes an expander washer movable axially of and encircling said plug member and carrying said thrust surface in compressing relation against said second clamping washer, an adapter washer movable axially of said plug member and having a thrust surface bearing against said expander washer and having an annular beveled surface bearing against the peripheral surface of the core plug hole to adapt the heater within limits to core plug holes of various diameters, and a nut threaded onto the plug member and bearing against said adapter washer to cause said clamping washers and sealing element to be compressed and seal said plug member within the core plug hole in the engine.

10. The structure defined in claim 8 wherein each of said clamping washers has an inclined circumferential surface and is made of a material harder than the material in the automotive engine in which it is mounted.

11. The structure defined in claim 8 wherein each of said clamping washers has a circumferential surface which is inclined axially inwardly toward said abutment means and is made of a material harder than the material in the automotive engine in which it is mounted.

ANTHONY BARTIS,

References Cited Primary Examiner U.S. Cl. X.R. 

